Test flag experiment access datasets

To test:

When retrieving investigations, it oculd be interesting to know if the user can access to the datasets or not.

A user cannot access to the experiment's datasets if the investigation is under embargo (ie. releaseDate > now) and he/she is not a participant and he/she is not instrumentScientisit on the experiment's instruments.

To check this, we are missing the list of investigationUsers and instrumentScientists, as we don't load them while loading the investigations. A user can see the list of the investigationUsers/instrumentScientists, so it should be possible, but this will increase the loading time, to be checked how.

At least, we could add a query parameter to indicate if we want this information (default is not).